The present invention relates to an automatically operable valve and more particularly to a shutoff valve for use with a fluid leak detector.
In hydraulic systems for aircraft, particularly military aircraft which might be subjected to gun fire, provisions must be made to isolate a ruptured or broken hydraulic line so that fluid from a main reservoir will not become exhausted and render inoperative other branches of a hydraulic system, as well as the ruptured branch. Various types of shutoff valves have been used to isolate a ruptured line. For example, in U.S. Pat. No. 2,493,906, entitled, "Vulnerability Valve", which issued Jan. 10, 1950, to Herbert W. Wishart, there is described a valve which will permit normal flow of actuating fluid to and through the lines of the branch of a hydraulic system but in the event that a line of the branch is ruptured, the valve will automatically isolate the branch from the fluid source.
In one military hydraulic system, a level sensing device is used on a fluid reservoir and, when the level in the reservoir reaches a low level, a pilot valve is actuated to switch fluid to close a shutoff valve. In the event of a high rate leak, however, such as a complete line failure, the loss of fluid can be so great that there will not be sufficient pressure to close the shutoff valve.